With the rapid progress of the display technique, the semiconductor element technique is also quickly developed as the core of the display device. In an existing display device, as a current-mode luminescent device, the Organic Light Emitting Diode (OLED) is increasingly applied into the field of high performance display due to its characteristics such as self-emission, quick response, wide viewing angle and being makeable on a flexible substrate.
The OLED may be classified into a Passive Matrix Driving OLED (PMOLED) and an Active Matrix Driving OLED (AMOLED) based on the driving mode. Due to the advantages such as low fabricating cost, high response speed, power saving, suitable for the direct current driving of the portable device, wide range of the working temperature, the AMOLED display is expected to be a new type of two-dimensional display to replace the Liquid Crystal Display (LCD). In the existing AMOLED display panel, each OLED includes a plurality of Thin Film Transistor (TFT) switching circuits, wherein due to the excellent static electrical characteristics, the low temperature poly silicon TFT, as an important electronic devices, has been widely used in the aspects such as liquid crystal display, matrix image sensor.